Pralidoxime

Indications:

Requires discussion with a clinical Toxicologist 

• Organophosphate poisoning – its use is controversial and is no longer routine o Nerve agent poisoning
• Antagonist to anticholinesterases such as neostigmine and pyridostigmine, which  are used in the treatment of myasthenia gravis. 

Formulation: 

• 500mg/20mL ampoule 

Dosage and Administration 

• Bolus dose:
  • In severe poisoning that is unresponsive to other treatments consider ∙ 1g pralidoxime iodide (15mg/kg paediatrics to 1g)
• Infusion:
  • Use 2.5g (5 ampoules) pralidoxime to give a final concentration of 2.5g in  100ml NaCl 0.9%
  • Run at a rate of 250mg/hr (10mg/kg/hr paediatrics)
  • Continue for 12 to 24hours and then review with toxicologist.
  • The infusion may be weaned over 24 to 48 hours, depending on the severity  of symptoms.
  • Cessation of the infusion is based upon clinical testing and mixed plasma  cholinesterase testing. 

Side Effects 

• Tachycardia
• Muscle rigidity
• Dizziness, blurred vision, diplopia, seizure. 
• Apnoea, Laryngeal spasm 

Pit Falls 

• Not effective in poisonings due to carbamates
• Dose adjustment is needed in renal impairment
• Use with great caution in treating organophosphate overdose in cases of myasthenia  gravis, as it may precipitate a myasthenic crisis.
• Response will depend on agent, severity and time to treatment